Thin oxides in the thickness range between 1 and 3 Inm are used in various transistor production methods, e.g. during the fabrication of polysilicon emitter devices. Such thin layers of silicon oxide have been used to modify the electrical performance of the device, and have been believed to prevent back-injection of the holes (or electrons) from the base into the emitter in an NPN (or PNP) device, thus improving the emitter efficiency and hence the gain. In application No. 831265, P. D. Scovell and R. L. Baker, filed Feb. 20th, 1986, abandoned and assigned to the same assignee as the present application, we have described a method for growing such layers, which method includes pulse-heating the semiconductor in an oxidising atmosphere to a peak temperature exceeding 500.degree. C.
The present invention has as its object an extension of the usefulness of such an oxide layer.